The stabilities of Meisenheimer complexes. Part 14. Equilibrium and kinetic data for sodium ethoxide addition to 2,4-dinitro-6-X-phenetoles in ethanol

Abstract

Equilibrium and kinetic data are reported for sodium ethoxide addition in ethanol to a series of 2,4-dinitro-6-X-phenetoles (X = NO₂, CO₂Et, Cl, or H) to give 1,1-σ complexes. In the case of 2,4,6-trinitrophenetole data for 1,3-complex formation are also provided. The results are compared with those for methoxide additions and are assessed in terms of the electronic and steric behaviour of the substituents. The 1,1-diethoxy-complexes, but not the 1,3-complex, associate strongly with sodium ions. It is suggested that this association involves interaction of the cation with the oxygen atoms of the alkoxy-groups at C(1) and the ortho-substituents.